1. Field of the Invention
The present invention relates to brazing material. More particularly, the present invention relates to a brazing material that is microalloyed to improve a characteristic of the brazing material.
2. Background Art
Base metals, including metals and metal alloys, can be joined in a number of different ways, such as by mechanical fastening, adhesive bonding, or using heat and a filler material to join the metals together. Metal joining techniques involving heat and filler materials are separated into three distinct classes known as soldering, brazing, and welding.
Soldering is a relatively low temperature metal joining process, which occurs at temperatures below 840° F. (450° C.). Soldering is a metallurgical bonding technique which involves the melting of a soldering alloy material between the surfaces of metallic members which is then allowed to cool to a solid state to join the metallic members together. Soldering offers relatively low joint strength for metallurgically bonding a base metal to another base metal. Soldering is often used in the electronics industry where the parts to be joined are not in motion or susceptible to large loads, stresses or impact. Metals typically used as the base metal for soldering alloys include lead, tin or zinc.
Welding is the highest temperature metal joining processes. Welding is used to join metal pieces together by raising the temperature at the seam between the base metals to be joined so that they are united by fusing, forging or pressure. Welding involves high temperatures that are close to the melting point of the base metals being joined, which is typically above 1830° F. (1000° C.). A filler metal, typically in the form of a welding rod, is usually used during a welding process to fill in the gaps between the base metals being joined and to facilitate the joining of the base metal metallurgically.
Brazing is a metal joining process that occurs at temperatures between those for soldering and welding. A braze joint offers higher joint strength (shear strength) than that of soldered. Referring to FIG. 1, brazing temperatures are above the melting point of the filler metal (braze 24) used and below the melting point of the base metals 20, 22 being joined. Brazing typically occurs at temperatures between 1100° F. and 1800° F. (600° C. to 1000° C.). Since the base metals 20, 22 are not melted by brazing, they typically retain most of their physical properties and the danger of metal distortion or warping, associated with welding, is minimized. Also, unlike soldering, brazing provides a strong metallic bond between the filler metal 24 and the base metals 20, 22 being joined. A properly made braze joint (like a weld joint) can in many cases be as strong as or stronger than the base materials themselves. However, brazing is typically more economical than welding because it is performed at lower temperatures and does not require the higher level skill set, accuracy, and attention to detail of welding. Metal alloys typically used as braze material (braze 24) include aluminum, copper, nickel, silver, or gold based alloys.
For brazing applications in particular, there is a desire for new or improved braze alloys that offer improved characteristics, such as higher braze strength and/or improved corrosion resistance. Also, in general, there is a desire for a brazing material that offers improved braze strength without significantly increasing braze temperature.